I’ve written this as a function so that you can update multiple calendars at the time. If you saved this as a .ps1 file and then run it, the 2 calendars referenced at the bottom would be updated. Alternatively you could . source the file and use the function interactively, or just hard code the $siteUrl and $calendarName variables each time you run it.

The option is removed immediately you have run the script with no iisreset or application pool recycle required.

So with the script is run this is what you see with the Meeting Workspace option removed:

This works well for hiding it on individual calendar lists, but doesn’t affect any other existing calendars or ones created afterwards.